Fastening Structure and Keyboard Device

ABSTRACT

A fastening structure for fastening a to-be-fastened component to a wooden component by using a screw, wherein the wooden component is made of wood having a specific gravity of 0.08 g/cm3 to 0.85 g/cm3 inclusive, the screw has a nominal diameter of 0.8 mm to 3.5 mm inclusive, and the distance between a neutral position in a longitudinal direction of an effective screw part, which is the portion where the wooden component and a male screw part formed in a shaft part of the screw mesh together, and the surface of the wooden component that comes into contact with the to-be-fastened component is 1 mm to 15 mm inclusive.

PRIORITY CLAIM

This application is continuation application of a PCT Application No.PCT/JP2018/011404, filed Mar. 22, 2018, entitled “FASTENING STRUCTUREAND KEYBOARD DEVICE” whose priority is claimed on Japanese PatentApplication No. 2017-058077, filed Mar. 23, 2017. The descriptionthereof is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a fastening structure and a keyboarddevice.

Description of Related Art

Conventionally, it is a well-known structure that fastens ato-be-fastened component to a wood component by fastening a screwpenetrating the to-be-fastened component to the wood component.

Japanese Unexamined Patent Application, first Publication No.2002-266824 (JP-A 2002-266824) discloses a structure in which two woodcomponents are fixed using a nail having a screw function that bitesinto wood by being turned with a driver, in addition to a function thatbites into wood by being hammered.

Wood components expand by moisture absorption and contract by drying.For this reason, when a wood component to which a to-be-fastenedcomponent has been fastened by a screw absorbs moisture, the woodcomponent expands, and a force acts on the screw in a direction of beingpulled out from the wood component. As a result, there is a risk of thewood component being plastically deformed and undergoing wear at theportion engaged with the male screw portion of the screw.

When the wood component in which a portion meshed with the male screwportion has undergone plastic deformation dries, a gap is generatedbetween the to-be-fastened component and the wood component. This gapleads to a risk of the fastening condition between the to-be-fastenedcomponent and the wood component loosening. When the fastening structureis included in various musical instruments (for example, an acousticpiano), the loosening of the fastening structure adversely affects theperformance of the musical instrument, and so is not particularlypreferable.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-mentionedcircumstances. The present invention therefore has as its object toprovide a fastening structure and a keyboard device capable ofsuppressing loosening of a fastened state between a to-be-fastenedcomponent and a wood component even if the wood component expands orcontracts.

In order to solve the aforementioned issue, the present inventionprovides the following means.

A fastening structure for fastening a to-be-fastened component to a woodcomponent by using a screw, in which the wood component is made of woodhaving a specific gravity of 0.85 g/cm³ or less, the screw has a nominaldiameter of 3.5 mm or less, and the distance between an intermediateposition in a longitudinal direction of an effective screw portion,which is the portion where the wood component and a male screw portionformed on a shaft portion of the screw mesh together, and a contactsurface of the wood component with the to-be-fastened component is 8 mmor less.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an example of the fasteningstructure of the first embodiment.

FIG. 2 is a cross-sectional view showing a modified example of thefastening structure of the first embodiment.

FIG. 3A is a cross-sectional view showing the contact surface in thefastening structure of the second embodiment.

FIG. 3B is a cross-sectional view along the lengthwise direction of thescrew, in the fastening structure of the second embodiment.

FIG. 4 is an exploded perspective view showing a modification of thefastening structure of the second embodiment.

FIG. 5 is a cross-sectional view showing an example of the fasteningstructure of the third embodiment.

FIG. 6 is a cross-sectional view showing an example of the fasteningstructure of the fourth embodiment.

FIG. 7 is a perspective view showing the main parts of a keyboarddevice.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described on the basis ofpreferred embodiments.

FIG. 1 schematically shows an example of a fastening structure of thefirst embodiment.

The fastening structure of the present embodiment is provided with awood component 10, a to-be-fastened component 20, and a screw 30. Ashaft portion 32 of the screw 30 is passed through the to-be-fastenedcomponent 20 to be fastened to the wood component 10, whereby theto-be-fastened component 20 is fastened to the wood component 10.

In the present embodiment, the length of the screw 30 is 30 mm or less.The thickness of the wood component 10 is about 30 mm.

The wood constituting the wood component 10 preferably has a specificgravity of 0.08 g/cm³ to 0.85 g/cm³. Balsa wood, for example,corresponds to a wood having a specific gravity of 0.08 g/cm³. Indianrosewood, for example, corresponds to a wood having a specific gravityof 0.85 g/cm³.

It is easy to obtain long members suitable for musical instrument parts,such as wood keys, from soft materials such as softwoods, which have alow specific gravity. Examples of the specific gravity of the woodcomponent 10 are about 0.85 g/cm³, about 0.7 g/cm³, about 0.6 g/cm³,about 0.5 g/cm³, about 0.4 g/cm³, about 0.3 g/cm³ and the like.

While not being specifically limited, the to-be-fastened component 20can be constituted from a resin, a metal, a base material, and the like.The screw 30 has a head portion 31 and a shaft portion 32. The headportion 31 is provided at one end of the shaft portion 32. Examples ofthe head portion 31 of the screw 30 include, but are not limited to, apan head, a countersunk head, a round countersunk head, a cheese head, atruss head, a bind head, a low head, and the like. The head portion 31is provided with a drive recess for turning the screw 30 with a toolsuch as a driver. Examples of the drive recess include a slot (groove),cross slot, a hexagonal hole, a square hole and the like.

The head portion 31 has a seat surface at the boundary with the shaftportion 32 as a portion which receives a direct force when the screw 30is tightened. The shape of the seat surface includes a flat surface, aconical surface and the like. If the seat is non-planar, the entire seatis included in the head portion 31.

A male screw portion 33 is formed on the shaft portion 32. The malescrew portion 33 may be formed up to the vicinity of the seat surface ofthe head portion 31. Examples of the shape of the male screw portion 33include a triangular screw, a square screw, a trapezoidal screw, and alight bulb screw. The shaft portion 32 between the head portion 31 andthe male screw portion 33 may be provided with a cylindrical portionhaving no screw thread and no screw groove.

Examples of a screw for being fastened to the wood component 10 includea wood screw, a tapping screw, and the like. As the screw 30, a screwhaving a nominal diameter D of 0.8 mm to 3.5 mm inclusive is used.Examples of the nominal diameter of the screw 30 include about 1.6 mm,about 1.8 mm, about 2.1 mm, about 2.4 mm, about 2.7 mm, about 3.1 mm,and about 3.5 mm.

A portion around the shaft portion 32 in the to-be-fastened component 20is sandwiched between a surface 11 of the wood component 10 and the headportion 31 of the screw 30. A contact surface 12 is a portion of asurface 11 of the wood component 10 that is in contact with theto-be-fastened component 20 side. An axial vicinity portion 13 is arange extending in parallel with an axis A of the screw 30 from thecontact surface 12. An effective screw portion 34 is a portion at whichthe male screw portion 33 and the wood component 10 mesh with eachother.

A spacer may be interposed between the wood component 10 and theto-be-fastened component 20 for the purpose of fine adjustment of heightand angle, as will be described in detail later. In this case, the twoor more types of the to-be-fastened component 20 and the spacer can bereferred to as to-be-fastened components to be fastened to the woodcomponent 10.

In the fastening structure of the present embodiment, a distance L1between an intermediate position 35 in the longitudinal direction of theeffective screw portion 34 and the contact surface 12 of the woodcomponent 10 with the to-be-fastened component 20 is 1 mm and more and15 mm or less, and more preferably 8 mm or less. When the distance L1 isless than 1 mm, practical strength of the screw 30 no longer arises.Moreover, 15 mm, which is the upper limit of the distance L1, is about ½of the thickness 30 mm of the wood component 10, and it is consideredthat the fastening strength of the screw 30 does not change even if thedistance L1 is longer than 15 mm. By setting the distance L1 asdescribed above, even if expansion or contraction of the wood component10 occurs due to a change in temperature or humidity, since the distanceL1 between the effective screw portion 34 and the contact surface 12 isshort, the amount of displacement of the to-be-fastened component 20that abuts the wood component 10 is small.

When the wood component 10 has expanded at the time of moistureabsorption or the like, the to-be-fastened component 20 may be displacedin a direction in which the screw 30 is pulled out by the head portion31 along the lengthwise direction of the screw 30. When the displacementamount of the to-be-fastened component 20 is large, the force in thedirection of pulling out the screw 30 acts more strongly. As a result,plastic permanent deformation occurs in the meshing between the malescrew portion 33 and the wood component 10, leading to the risk ofdeterioration or damage to the fastening structure and loosening of thefastened state.

It is also conceivable to provide a spring washer on the screw 30 toabsorb the displacement of the to-be-fastened component 20. However,adding another part leads to the risk of handling becoming difficultduring fastening work, a rise in cost, and a deterioration inappearance.

When the displacement amount of the to-be-fastened component 20 issmall, the structure of the wood component 10 meshing with the malescrew portion 33 undergoes viscoelastic deformation, and a fasteningstructure capable of reversibly absorbing the displacement isconfigured.

During expansion of the wood component 10, a target range for exertingan effect on the displacement of the to-be-fastened component 20 isestimated to be approximately the range of the distance from the contactsurface 12 to the effective screw portion 34. The average position ofthe meshing position with the male screw portion 33 is an intermediateposition 35 of the effective screw portion 34. The distance L1 betweenthis intermediate position 35 and the contact surface 12 indicates thesize of the target range in which the head portion 31 of the screw 30 isdisplaced via the to-be-fastened component 20 when the wood component 10is expanded. That is, the magnitude of the distance L1 is reflected inthe magnitude of the displacement amount of the to-be-fastened component20 with respect to the intermediate position 35 at the time of expansionof the wood component 10.

For this reason, in order to reduce the displacement amount of theto-be-fastened component 20, a reference can be set by defining an upperlimit to the distance L1 between the intermediate position 35 and thecontact surface 12. That is, if the target range affecting thedisplacement of the to-be-fastened component 20 is shortened when thewood component 10 is expanded, the amount by which the screw 30 ispulled out in the vicinity of the effective screw portion 34 is reduced.As a result, the amount by which the screw 30 is pulled out tends tofall within the range in which the wood structure is reversiblydeformed.

The upper limit value of the distance L1 can also be experimentallyfound, for example, for a fastening structure to a soft material such asa softwood. When the distance L1 is 8 mm or less, loosening of the stateof the fastening structure is effectively prevented. Examples of thedistance L1 include, but are not particularly limited to, about 8 mm,about 7 mm, about 6 mm, about 5 mm, about 4 mm, about 3 mm, and thelike.

In general, using a short screw having a small nominal diameter for asoft material such as a softwood causes an absolute lack of strength andlacks reliability because a fastening condition is not determined, andso has been avoided. A state in which the fastened screw is suitablyloosened may, depending on the application, contribute to theflexibility of the structure, and using multiple screws to provideredundancy can extend the scope of application. However, when fasteningparts used in a musical instrument with a screw, particularly when thefastened parts have a function to control the sound or operation of theinstrument, slight noises or operational rattling due to loosening ofthe screw can be a problem.

In the example shown in FIG. 1, the wood component 10 is provided with apilot hole 14 in order to facilitate fastening of the screw 30 to thewood component 10. The inner diameter of the pilot hole 14 is narrowerthan the shaft portion 32 of the screw 30 in order to facilitate meshingof the male screw portion 33 with the inner surface of the pilot hole14.

FIG. 2 schematically shows a modified example of the fastening structureof the first embodiment. Note that illustration of the to-be-fastenedcomponent 20 is omitted in FIG. 2. In the example shown in FIG. 2, thescrew 30 meshes with the wood component 10 without providing a pilothole in the wood component 10. Moreover, in the example shown in FIG. 2,a recess 15 is formed on the opposite side to the contact surface 12 ofthe wood component 10. As shown in the drawing, the male screw portion33 is not meshed with the wood component 10 in the recess 15. For thatreason, the range in which the male screw portion 33 is exposed in therecess 15 is excluded from the effective screw portion 34.

FIGS. 3A and 3B schematically show an example of the fastening structureof a second embodiment. FIG. 3A is a transverse cross-sectional view ofthe contact surface 12, and FIG. 3B is a longitudinal cross-sectionalview along the lengthwise direction of the screw 30. In the fasteningstructure of the present embodiment, the area of the contact surface 12is 100 mm² or less per screw. Similarly to the first embodiment, thespecific gravity of the wood component 10 is preferably 0.85 g/cm³ orless, and the nominal diameter of the screw 30 is preferably 0.8 mm ormore and 3.5 mm or less. Further, as in FIG. 1, it is preferable thatthe distance L1 between the intermediate position 35 of the effectivescrew portion 34 and the contact surface 12 of the wood component 10 be1 mm or more and 15 mm or less, and more preferably 8 mm or less.

Accompanying the fastening of the screw 30, an acting/reacting loadbetween the wood component 10 and the to-be-fastened component 20 isconcentrated on the contact surface 12. Therefore, in the presentembodiment, by providing an upper limit to the area of the contactsurface 12, a layer on the surface 11 side near the contact surface 12of the wood component 10 can be compressively deformed in a reversiblemanner. By combining the condition of setting the upper limit to thedistance L1 and the condition of setting the upper limit to the area ofthe contact surface 12 per screw, together with the effect that the woodstructure meshing with the effective screw portion 34 is reversiblydeformed, it is possible to extend the effect of preventing loosening ofthe screw 30.

The upper limit of the area of the contact surface 12 per screw can alsobe determined experimentally for a fastening structure to, for example,a soft material such as softwood. When the area of the contact surface12 per screw is 100 mm² or less, loosening of the fastening structure iseffectively prevented. Examples of the area of the contact surface 12per screw include, but are not particularly limited to, about 100 mm²,about 90 mm², about 80 mm², about 70 mm², about 60 mm², about 50 mm²,about 40 mm², and about 30 mm².

In order to narrow the area of the contact surface 12 per screw, one ormore projections may be provided on at least one of the surface 11 ofthe wood component 10 and a back surface 21 of the to-be-fastenedcomponent 20. FIG. 4 schematically shows a modification of the fasteningstructure of the second embodiment. In the example shown in FIG. 4, aplurality of projections 22 are formed on the back surface 21, which isthe side of the to-be-fastened component 20 facing the wood component10.

The total area over which the plurality of projections 22 correspondingto one screw 30 abut the wood component 10 is the area of the contactsurface 12 per screw. The shape of the projections 22 is notparticularly limited, and may be, for example, a crest shape, a dotshape, a boss shape, a rib shape and the like. When the projections 22are provided on at least one surface of the wood component 10 and theto-be-fastened component 20 that are facing each other, the distal endface of each projection 22 abuts with the component facing theprojection 22.

FIG. 5 schematically shows an example of the fastening structure of athird embodiment. In the present embodiment, a distance L2 between ato-be-pressed surface 23 of the to-be-fastened component 20 and thecontact surface 12 of the wood component 10 with the to-be-fastenedcomponent 20 is 2 mm or less. Here, the to-be-pressed surface 23 is aportion where the to-be-fastened component 20 is pressed from the headportion 31 of the screw 30.

As in the first embodiment, it is preferable that the specific gravityof the wood component 10 of this embodiment be 0.85 g/cm³ or less, andthe nominal diameter of the screw 30 be 0.8 mm to 3.5 mm. Further, as inFIG. 1, it is preferable that the distance L1 between the intermediateposition 35 of the effective screw portion 34 and the contact surface 12of the wood component 10 be 1 mm or more and 15 mm or less, and morepreferably 8 mm or less. Similarly to the second embodiment, the area ofthe contact surface 12 may be 100 mm² or less per screw.

When the to-be-fastened component 20 includes wood, the wood containedin the to-be-fastened component 20 expands due to moisture absorptionand shrinks due to drying. In addition, when the to-be-fastenedcomponent 20 is a non-wood material such as metal or resin, expansion orcontraction due to temperature is larger than that of wood, with theto-be-fastened component 20 expanding at a high temperature andcontracting at a low temperature.

When the to-be-fastened component 20 expands, the head portion 31 of thescrew 30 may be displaced in the direction in which the screw 30 ispulled out at the head portion 31 along the longitudinal direction ofthe screw 30. If the displacement of the head portion 31 is large, theforce in the direction of pulling out the screw 30 acts more strongly,whereby plastic permanent deformation may occur in the meshing betweenthe male screw portion 33 and the wood component 10, leading todeterioration or damage in the fastening structure and loosening of thefastened state.

Therefore, in this embodiment, by providing an upper limit to thedistance L2 between the to-be-pressed surface 23 and the contact surface12, it is possible to reduce the absolute amount of expansion orcontraction of the to-be-fastened component 20, and inhibit loosening ofthe screw 30 caused by expansion or contraction of the to-be-fastenedcomponent 20. Examples of the distance L2 include, but are not limitedto, about 2 mm, about 1.5 mm, about 1 mm, about 0.5 mm, and the like.

When the seat surface of the head portion 31 of the screw 30 isnon-planar, the position of the to-be-pressed surface 23 may be aposition closest to the contact surface 12 among the portions where thehead portion 31 contacts the to-be-fastened component 20. When a washer(not shown) is interposed between the head portion 31 of the screw 30and the to-be-pressed surface 23 of the to-be-fastened component 20, thethickness of the washer may be excluded from the distance L2.

By combining the condition of setting the upper limit to the distance L1and the condition of setting the upper limit to the distance L2,together with the effect that the wood structure meshing with theeffective screw portion 34 is reversibly deformed, it is possible toextend the effect of preventing loosening of the screw 30.

When the to-be-fastened component 20 is made of wood having a specificgravity of 0.85 g/cm³ or less, as in the case of the wood component 10,an upper limit may be provided for the total of the distance L1 and thedistance L2, that is, the distance between the intermediate position 35of the effective screw portion 34 and the to-be-pressed surface 23 ofthe to-be-fastened component 20. Letting the total of the distance L1and the distance L2 be L3, the distance L3 is preferably 10 mm or less.

Examples of the distance L3 include, but are not particularly limitedto, about 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, and the like.

FIG. 6 schematically shows an example of the fastening structure of thefourth embodiment. In the above-described fastening structure, theeffective thread 34 may be entangled with a dark ring 16 of the woodcomponent 10. Wood grown in a temperate zone to a cool zone usually hasdark rings 16 and light rings 17 alternately formed due to thedifference in the growth rate of the cell wall depending on the season,resulting in annual rings. The dark rings 16 have a higher strength thanthe light rings 17, and variations due to characteristic differencesbetween the dark rings 16 and the light rings 17 are large. Therefore,when the male screw portion 33 meshes with a portion including the darkring 16, it is possible to enhance the viscoelastic reversibledeformation characteristics.

For example, a value (R/cos θ) obtained by dividing the average annualring interval R by the cosine of the angle θ formed by the axis A of thescrew 30 and the normal N of the annual ring surface in the vicinity ofthe effective screw portion 34 is the average distance of dark rings 16along the axis A. Therefore, by setting the length of the effectivescrew portion 34 to be larger than R/cos θ, it is possible to morereliably configure a fastening structure in which the effective screwportion 34 is entangled with dark rings 16.

Fastening with the screw 30 has excellent workability, with lessmanagement items than adhesion and the like. Further, since the screw 30is removable, when a spacer is interposed between the wood component 10and the to-be-fastened component 20, the height and angle can beadjusted by trial. When the to-be-fastened component is fixed byadhesion or the like, subsequent removal and reattachment is difficulteven if one tries to make fine adjustments to the height or angle of theto-be-fastened component. For this reason, for example, when fixing afunctional component to a wood component such as a wood key in akeyboard instrument, quality stability and improvement of workabilitycan be achieved by fastening the functional component to the woodcomponent with a screw. By making the functional component detachablefrom the wood component, replacement with spacers having differentheights and angles becomes possible.

Examples of functional components for musical instruments includeoperating force transfer members (a switch drive (SW) actuator, hammerdrive actuator, after sensor pusher, and the like), operation detectionmeans (a sensor, reflector, gray scale, shutter plate, and the like),key guide mechanisms, key movement control mechanisms (rest, key dipblock, L foot and the like), shock absorbing materials (felt, rubber,foam material and the like), mass bodies (counterweight and the like),and protective plates (grease cover and the like). The musicalinstrument is not particularly limited, and examples thereof include akeyboard instrument such as a piano, a string instrument such as a harp,a percussion instrument, and a wind instrument.

FIG. 7 schematically shows the main parts of the keyboard device in akeyboard instrument. FIG. 7 shows one white key 41W and one black key41B of a keyboard device 40. The wood key 41 is a long part, andtherefore, it is advantageous to construct the wood key 41 from conifer,in which it is easy to obtain a member having high straightness of grainand having no excluded parts such as a knot over a certain distance. Abackcheck component 42 is fixed near one end of the wood key 41. Thebackcheck component is a mechanical part that receives the hammer, whichis included in the action mechanism (not shown) of the keyboardinstrument. When the wood key 41 is depressed, the hammer strikes thestring in conjunction with the movement of the key, and then reboundsand returns.

The backcheck component receives and brakes the motion of the returninghammer.

For example, when fixing the backcheck component 42 to the wood key 41,the fastening structure of each of the above-described embodiments canbe adopted as a fastening structure by using the screw 30. In this case,components to be fastened to the wood key 41 include the backcheckcomponent 42 and a spacer. When a spacer is interposed between the woodkey 41 and the backcheck component 42, the position of the contactsurface 12 of the wood component 10 with the to-be-fastened component 20shown in FIG. 1 may be a position of the surface on which the wood keymakes contact with the spacer.

A counterweight is sometimes affixed to the wood key of the keyboarddevice as a mass body for achieving balance with an action part such asa hammer. When the counterweight is affixed to the wood key, it ispossible to accommodate the counterweight in a recess formed in the woodkey and fasten the counterweight to the wood key using a screw. Thefastening structure of each embodiment described above can be employedas the fastening structure between the wood key and the counterweight.

Although the present invention has been described above based on thepreferred embodiments, the present invention is not limited to theabove-described embodiments, and various modifications can be madewithout departing from the scope of the present invention.

Although a musical instrument has mainly been described in the aboveembodiments, the present invention is not limited thereto. Theabove-described fastening structure is suitable, for example, toapplications in which another component is fastened to a long woodcomponent, and a fastening state that is not easily loosened isrequired. Examples of other applications include, for example, crafts,gadgets and the like.

Moreover, the screw used in the embodiments described above is notlimited to a general single-thread screw, with a double-thread screwalso usable. In a single-thread screw, the distance the screw advancesin one turn (lead) is equal to the pitch, and so the screw moves onepitch in one rotation. In a double thread screw, there are helices oftwo threads in one pitch, and so the lead is twice as large as asingle-thread screw.

According to the embodiments of the present invention described above,even if the wood component expands or contracts, it is possible tosuppress loosening of the fastening state between the to-be-fastenedcomponent and the wood component.

What is claimed is:
 1. A fastening structure for fastening ato-be-fastened component to a wood component by using a screw, whereinthe wood component is made of wood having a specific gravity of 0.08g/cm³ to 0.85 g/cm³ inclusive; the screw has a nominal diameter of 0.8mm to 3.5 mm inclusive; and the distance between an intermediateposition in a longitudinal direction of an effective screw portion,which is the portion where the wood component and a male screw portionformed on a shaft portion of the screw mesh together, and a contactsurface of the wood component with the to-be-fastened component is 1 mmto 15 mm inclusive.
 2. The fastening structure according to claim 1,wherein the area of the contact surface is 100 mm² or less per screw. 3.The fastening structure according to claim 2, wherein a plurality ofprojections are provided on at least one surface of the wood componentand the to-be-fastened component that are facing each other.
 4. Thefastening structure according to claim 1, wherein a distance between ato-be-pressed surface where the to-be-fastened component is pressed fromthe head portion of the screw and the contact surface is 2 mm or less.5. The fastening structure according to claim 1, wherein the effectivescrew portion is entangled with a dark ring of the wood component.
 6. Akeyboard device having a fastening structure for fastening ato-be-fastened component to a wood key by using a screw, wherein thewood key is made of wood having a specific gravity of 0.08 g/cm³ to 0.85g/cm³ inclusive; the screw has a nominal diameter of 0.8 mm to 3.5 mminclusive; and the distance between an intermediate position in alongitudinal direction of an effective screw portion, which is theportion where the wood key and a male screw portion formed on a shaftportion of the screw mesh together, and a contact surface of the woodkey with the to-be-fastened component is 1 mm to 15 mm inclusive.
 7. Thekeyboard device according to claim 6, wherein the to-be-fastenedcomponent is a backcheck component.
 8. The fastening structure accordingto claim 6, wherein the area of the contact surface is 100 mm² or lessper screw.
 9. The fastening structure according to claim 6, wherein aplurality of projections are provided on at least one surface of thewood key and the to-be-fastened component that are facing each other.10. The fastening structure according to claim 6, wherein a distancebetween a to-be-pressed surface where the to-be-fastened component ispressed from the head portion of the screw and the contact surface is 2mm or less.
 11. The fastening structure according to claim 1, whereinthe effective screw portion is entangled with a dark ring of the woodkey.